package homework;

import java.util.Scanner;

public class work04 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s1 = sc.next();
		String s2 = sc.next();
		sc.close();
		System.out.println(same(s1,s2));
	}	
	public static String same(String s1,String s2){
		String max="";String min="";
		max=(s1.length()>s2.length())? s1:s2;
		min=(max==s1)? s2:s1;
		for(int x=0;x<min.length();x++){
			for(int y=0,z=min.length()-x;z!=min.length()+1;y++,z++){
				String temp=min.substring(y, z);
				if(max.contains(temp)){
					return temp;
				}
			}
		}
		return null;
	}
}
